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Secret to human AIDS vaccine may be found in feline virus

Researchers from the University of Florida and the University of California, San Francisco, have found that certain peptides of the feline immunodeficiency virus (FIV) can produce human T cells that fight against human immunodeficiency virus (HIV). The surprise discovery sets the stage for an HIV vaccine derived from a particular peptide region of the FIV virus.

“We found that one particular peptide region on FIV activated the patients’ T cells to kill the HIV,” says Janet Yamamoto, PhD, a professor of retroviral immunology at the UF College of Veterinary Medicine and the study’s corresponding author. “One major reason why there has been no successful HIV vaccine to date is that we do not know which parts of HIV to combine to produce the most effective vaccine.”

In previous studies, Yamamoto says, scientists have combined various whole HIV proteins as vaccine components, but none have worked well enough to be used as a commercial vaccine. The researchers in this study isolated T cells from HIV-positive individuals and incubated these cells with different peptides that are crucial for survival of both HIV and FIV. They then compared the reactions they got with FIV peptides to what they found using HIV-1 peptides. “In humans, some peptides stimulate immune responses, which either enhance HIV infection or have no effect at all, while others may have anti-HIV activities that are lost when the virus changes or mutates to avoid such immunity,” Yamamoto says.

What the research revealed was a specific viral peptide in FIV that does not mutate and can induce anti-HIV T cell activities. However, while T cell peptides can prompt the body’s T cells to recognize viral peptides on infected cells and attack them, Yamamoto says not all HIV peptides can work as vaccine components.

In fact, she says a T cell-based vaccine has never been used to prevent any viral diseases. “So we are now employing an immune system approach that has not been typically utilized to make a vaccine,” Yamamoto says. “The possible use of the cat virus for this vaccine is unique.”

As a researcher at the University of California-Davis, Yamamoto discovered FIV in 1986, along with fellow professor Niels C. Pederson. She went on to co-develop the FIV vaccine made available to veterinarians in 2002. Michael Murphey-Corb, PhD, a professor in the department of microbiology and molecular genetics at the University of Pittsburgh, says, “Dr. Yamamoto has identified the immunological Achilles’ heel of HIV.”